HYDRATED  SILICA  AND  SILICATE  OE  AMMONIA, 
47 
extremely  small  quantity  of  green  coloring  matter,  seemingly 
deposited  only  or  principally  in  its  outer  layer.  By  demonstra- 
ting the  concurrence  of  chlorophyll  in  cells  which  contained  no 
starch,  or  the  growth  of  the  green  globules  after  the  starch- 
grains  have  vanished,  and  in  other  cases  the  simultaneous  in- 
crease of  starch  and  chlorophyll  grains  in  the  same  cells,  Mohl 
Las  shown  the  groundlessness  of  Mulder's  hypothesis,  that  chlo- 
rophyll is  formed  of  starch  altered  by  deoxydation,  and  that  the 
evolution  of  oxygen  by  green  foliage  is  merely  the  result  of  this 
supposed  transformation  of  starch  into  green  coloring  matter  and 
wax  ;  and  he  maintains  that,  by  appropriate  evidence,  he  has 
abundantly  demonstrated  the  principal  mass  of  chlorophyll-grains 
to  consist  of  a  substance  allied  to  protoplasm,  which  certainly  can- 
not originate  from  a  metamorphosis  of  the  constituents  of 
starch  A.  g.  Sillimari's  Journal,  Sept.  1855. 
ON  HYDRATED  SILICA  AND  SILICATE  OF  AMMONIA, 
By  J.  Liebig. 
According  to  some  experiments  of  Liebig,  the  solubility  of 
Silica  in  water  depends  essentially  upon  the  circumstance  whether 
or  no  a  sufficient  quantity  of  water  for  its  solution  is  present  at 
the  moment  that  it  is  separated  from  an  alkaline  silicate.  If  a 
sufficient  quantity  of  water  be  present,  a  much  larger  quantity 
of  silica  dissolves  than  when  water  is  saturated  with  gelatinous 
silica. 
If  a  solution  of  soluble  silicate,  the  strength  of  which  per 
cubic  centimetre  is  known,  be  gradually  diluted  with  measured 
Quantities  of  water,  a  point  may  be  arrived  at  when,  on  the 
addition  of  an  acid  (muriatic  acid)  in  slight  excess,  the  fluid 
remains  perfectly  clear,  and  no  silica  is  separated.  From  ex- 
periments it  appears  that  by  this  process  water  will  dissolve  as 
much  as  l-500th  of  silica. 
Ammonia,  like  carbonate  of  ammonia,  diminishes  the  solu- 
bility of  silica  in  water;  for  when  a  few  drops  of  ammonia  have 
been  added  to  the  solution  above  described  before  the  addition 
of  acid,  a  fluid  is  obtained,  which  does  not  remain  clear,  but 
becomes  opalescent,  and  finally  gelatinous.  Muriate  of  ammonia 
produces  the  same  effect,    A  solution  of  carbonate  of  ammonia7 
